Update imports in snip12 doc code blocks

[andrew-fleming]

This PR also proposes to reorder the imports as well by alphabetizing them via scarb fmt. We can change this back if it's preferred to have the openzeppelin import at the top

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 91.53%. Comparing base (f7b7a7b) to head (7e68a3d).
Report is 2 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1182   +/-   ##
=======================================
  Coverage   91.53%   91.53%           
=======================================
  Files          46       46           
  Lines        1182     1182           
=======================================
  Hits         1082     1082           
  Misses        100      100           

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[ericnordelo]

Good catch! LGTM